The aim of this thesis is to describe and defend ‘The Constraint-Based View’, which is a particular conception of the nature of, and relationship between, ideal and non-ideal theories of justice. Traditionally, ideal theory is characterised by the assumption of ‘full compliance’, while non-ideal theory is characterised by the assumption of ‘partial compliance’. In other words, ideal theories assume that those for whom the theory is meant to apply will be entirely willing and able to comply with the theory’s requirements, while non-ideal theories do not. In Chapter 1 of this thesis, I describe and assess this original conception as well as several alternative accounts of ideal and non-ideal theory, in order to offer a broad survey of the existing literature, and to identify the various ways that these conceptions fail to capture fully the relationship between ideal and non-ideal theory. In Chapter 2, I draw a distinction between two different approaches to theorising about justice. ‘Axiological’ or ‘A-Type’ approaches are characterised by the fact that they include almost no assumptions as inputs to the theory, and that they are not intended to provide action-guiding recommendations as part of the outputs of the theory. In contrast, ‘Practical’ or ‘P-Type’ approaches include additional assumptions as part of their inputs and are intended to form part of a process that ultimately produces action-guiding recommendations. In Chapter 3, I describe and defend my preferred conception of the relationship between ideal and non-ideal theory – the ‘Constraint-Based View’ (CBV). According to the CBV, there is a spectrum of theoretical approaches that can be more or less ideal, depending on the extent to which they include ‘soft constraints’ as part of the inputs to the theory. Soft constraints are facts about the world that can be changed, in contrast to hard constraints, which are facts about the world that cannot. I argue that this way of thinking about the relationship between ideal and non-ideal theory is more useful than the alternative conceptions considered in Chapter 1. In Chapter 4, I examine the roles that feasibility considerations should play in ideal and non-ideal theory, from the perspective of the CBV and in Chapter 5, I explain the implications of adopting the CBV for what I call ‘transitional theory’, which is concerned with the transition from the status quo towards a more ideal state of affairs. In Chapter 6, I offer an example of the CBV in action, by considering its implications for the debate over duties of justice towards future generations.

[pt] Teorias ideais e teoria não-ideais da adjudicação são uma distinção metodológica dentro das teorias normativas da adjudicação. A última considera que a metodologia das teorias normativas deve ser adequada ao que podemos esperar de seres humanos ordinários. Autores do formalismo jurídico como Larry Alexander, Cass Sunstein e Adrian Vermeule estão associados a essa metodologia. O primeiro, por sua vez, considera que esta não é uma restrição normativamente relevante. Podemos defender teorias cujos padrões normativos violam o que podemos esperar de seres humanos ordinários. O particularismo de Dworkin é o principal expoente desse método. A pergunta central é se há um conflito genuíno entre esses dois métodos. Para responder essa pergunta, divido as teorias ideais em duas vertentes: teorias ideais não-orientador e teorias ideais orientadoras. Defendo que há um conflito metodológico apenas entre os métodos não-ideias e este último. Por fim, sugiro que a reflexão sobre esses métodos é importante para desenvolver novos projetos normativos, nomeadamente, do formalismo ideal e que tal empreitada é intelectualmente valiosa. / [en] Ideal theories and non-ideal theories of adjudication are a methodological distinction within normative theories of adjudication. The latter consider that the methodology of normative theories must be adequate to what we might expect from ordinary human beings. Legal formalist scholars such as Larry Alexander, Cass Sunstein e Adrian Vermeule are associated with this methodology. The latter, in turn, believe that this is not a normatively relevant constraint. We can defend theories whose normative standards violate what we might expect from ordinary human beings. Dworkin s particularism is the chief exponent of this method. The central question is whether there is a genuine conflict between these two methods. To answer this question, I divide ideal theories into two strands: non-orienting ideal theory and orienting ideal theory. I argue that there is a methodological conflict only between non-ideals and the latter. Finally, I suggest that reflection on these issues is important to developing new normative projects, namely, ideal formalism and that such enterprise is intellectually valuable.

L’objectif général de ce travail est d’étudier certains problèmes d’éthique et de philosophie politique soulevés par le changement climatique et de proposer des politiques susceptibles de réduire les injustices climatiques. La première partie vise à justifier les devoirs majeurs de justice climatique à partir d’une approche centrée sur les droits humains menacés par le changement climatique. Les données des sciences du climat et des œuvres de fiction littéraires et cinématographiques servent comme fondement de la réflexion philosophique. La deuxième partie explore certaines pistes de réformes institutionnelles à même de réaliser ces devoirs de justice globale et intergénérationnelle. Il s’agit d’exclure certaines réponses proposées au changement climatique, comme la géoingénierie et la compensation, mais aussi et surtout de développer des politiques justes, efficaces et faisables de réduction des émissions de gaz à effet de serre, comme un cadre normatif pour évaluer les engagements des pays, un mécanisme de marché hybride et un rôle politique accru accordé à la société civile. Si ce travail s’inspire des recherches des scientifiques, des écrivains, des économistes et des spécialistes des relations internationales, il dialogue principalement avec les auteurs les plus influents en justice et en éthique climatiques. Au final, bien que les défis moraux et politiques posés par le changement climatique soient sans précédent, l’approche non idéale de la justice climatique développée ici montre qu’il est encore temps d’agir pour éviter les scénarios les plus nuisibles pour les pauvres du monde et les générations futures. / The main objective of this work is to highlight key philosophical problems raised by climate change and to propose policies that could reduce climate injustices. In the first part, I justify major duties of climate justice by constructing a normative approach focusing on basic human rights threatened by climate change. My philosophical reflections draw on data provided by climate sciences as well as works of literary and cinematographic fiction. In the second part, I explore possible institutional reforms that could realize these duties of global and intergenerational justice. My point is to reject false solutions such as geoengineering and offsetting, but also and mostly to develop just, efficient and feasible policies such as a normative framework to assess the equity of countries’ pledges, a hybrid market mechanism and an increased political role given to civil society. While this work draws on researches made by scientists, writers, economists and international relations scholars, it also critically engages with the theories of the most influent authors in climate justice and climate ethics. The non-ideal approach of climate justice I develop explains that even if the moral and political challenges raised by climate change are unprecedented, it is not too late to prevent the realization of the most harmful scenarios for the global poor and future generations.